With thanks to Steve for these pics.
Benjamin 312 1940s (boxed)
With thanks to American Vintage Airguns forum member Yngathrt.
D T Fletcher said: "The 310-312-317-710 were all introduced at the same time, circa 1939-1940. I have always leaned towards 1940, if for no other reason that 1940 was when the applicable Crosman patent ran out. But, what is sure is that the new “MULTIPLE LEVER HAND PUMP ACTION” was introduced in 1939. The clue that indicates this is an AP Spack letter to dealers announcing the new "multiple lever" design still has the "St. Louis, MO. U.S.A." address used by Benjamin for the original Wissler Instrument downtown building. In 1939, Benjamin moved operations to 8th St. and all Benjamin paper after 1939 carry that address. There is an AP Spack letter dated March 5, 1940, and the address is 8th & Marion, so, by 1940 all production is in the new plant with the new models.
In what looks like the first full catalog to feature the new 310---710 line, it has the old St, Louis address but shows a picture of the new plant and describes production in the new facility."
Benjamin 312 (1940-1942)
With thanks to Marty for these pics. He said: "I purchased this gun last week & am fortunate several items & documents accompanied the gun. The most significant of which are; 1940-1942 'Be Prepared!' Patriot Minute Man w/green background, the 'Valuable Information' pamphlet dated January 1, 1942, & the 'Instruction Sheet For Benjamin Air Rifles'. This pamphlet shows Benjamin Steel Dart, Cal. .22, per dozen (out of stock) 1940-1942.
Additional items; 'Registration Card' consistent with early model Benjamin's, 'H C Benjamin' pellets consistent with early Benjamin ammo, 'Western Steel Air Rifle Shot- Trev's Airgun Scrapbook with caption; "Western Air Rifle Shot Advert, 1940", & '25 FEET 'BB' TARGET' consistent with Instruction Sheet 'Ammunition And Tools'."